1. Field of the Invention
This invention relates to an apparatus for exerting a pulling force on a grooved fastener pin extending through aligned holes in facially engaged workpieces. A jaw structure engageable with the fastener pin is radially offset from the axis of a piston actuated installation tool that is used to provide the operating force for pulling the fastener pin through the workpieces. The radial offset enables a nose portion of the apparatus to extend into partially obstructed clearance spaces that would not otherwise accommodate the nose portion is the nose portion were in direct axial alignment with the piston-cylinder axis of the tool.
2. Description of Prior Developments
A typical pin puller nose assembly includes an anvil housing having an annular nose portion adapted to engage a workpiece or a collar surrounding a grooved portion of a fastener pin that projects axially beyond the workpiece or collar. A segmented jaw structure is located within the nose portion of the anvil housing to grip the projecting portion of the pin for exerting an axial pulling force thereon.
The jaw structure is mounted within a collet that can move axially away from the workpiece or collar to initially clamp the jaw structure onto the grooved pin and to thereafter draw the jaw structure away from the workpiece surface. Axial movement of the collet is effective to either pull the pin through the workpiece and/or swage a fastener collar onto the fastener pin, depending on the particular usage of the apparatus.
The jaw structure segments typically include convergent nose surfaces axially aligned with an internal conical surface on the collet. As the collet moves away from the workpiece its internal conical surface exerts a camming action on the convergent nose surfaces of the jaw segments, thereby forcing the jaw segments to move radially inwardly so that teeth on the jaw segments exert gripping forces on the grooves of the fastener pin. The jaw structure is freely mounted within the collet so that initially the jaw segments are prevented from axial motion primarily by a relatively loose interlocking of the jaw segment teeth with the grooves in the fastener pin.
Under some conditions this loose interlocking fit of the jaw teeth in the fastener pin grooves is not fully effective to prevent undesired axial motion of the jaw structure such as occurs when the jaw segments slip axially along the pin surface. Such axial slippage is undesirable in that it requires the pin to be longer than it might otherwise have to be if the slippage did not have to be taken into account.
Aforementioned U.S. Pat. No. 4,989,442 provides a structural arrangement for preventing the undesired slippage of the jaw segments on the grooved fastener pin. The arrangements depicted in that patent application are structurally configured as in-line constructions wherein the nose of the anvil housing is in axial alignment with the axis of the piston-cylinder tool that is used to provide the operating force for the pin puller apparatus. Such an arrangement is not capable of operation in hard to reach applications requiring an offset nose configuration.